This invention relates to an improved carton for heating food products in a microwave oven, and more specifically to a carton of this type with integral support means and apertures for permitting the release of moisture during heating.
In U.S. Pat. No. 3,876,131 and U.S. Pat. No. Re29,185, it was recognized that packages useful for heating foods by microwave ovens must be vented to permit exhaustion of moisture vapors generated during the heating process, but yet must be sealed for protection of the food during shipment and storage. To meet these criteria, these patents disclosed placing apertures in the bottom of the carton and covering these with a strip of film which could be removed prior to heating.
It was also found important to elevate the bottom surface of the carton from the microwave oven shelf so that the moist gases could be more efficiently exhausted from the container. This requirement was met by provision of side wall panels which extended downwardly below the plane of the bottom surface of the container. In effect, the side walls formed legs which raised the container above the support surfaces.
While the provision of downwardly extending side walls does provide for efficient exhaustion of gases from the container, these protrusions from the plane of the bottom surface require the employment of extra material in manufacturing and cause additional limitations on the configurations in which the packages can be placed in shipping cases.